RT9179A Adjustable, 500mA LDO Regulator with Enable Features General Description 400mV Dropout @ 500mA 150 A Low Quiescent Current The RT9179A is a high performance linear voltage regulator with enable high function and adjustable output with a 1.175V reference voltage. It operates from an input of 3V to 5.5V and provides output current up to 500mA with two external resistors to set the output voltage ranges from 1.175V to 4.5V. Excellent Line and Load Regulation <1 A Standby Current in Shutdown Mode Guaranteed 500mA Output Current Adjustable Output Voltage Ranges from 1.175V to 4.5V Over-Temperature/Over-Current Protection RoHS Compliant and 100% Lead (Pb)-Free The RT9179A has superior regulation over variations in line and load. Also it provides fast response to step changes in load. Other features include over-current and overtemperature protection. The device has enable pin to reduce power consumption in shutdown mode. Applications Battery-Powered Equipments The device is available in SOP-8 package. Graphic Card Peripheral Cards PCMCIA Card Ordering Information RT9179A Package Type S : SOP-8 Pin Configurations (TOP VIEW) Lead Plating System P : Pb Free G : Green (Halogen Free and Pb Free) EN Note : Richtek products are : 8 GND VIN 2 7 GND VOUT 3 6 GND ADJ 4 5 GND RoHS compliant and compatible with the current requireSOP-8 ments of IPC/JEDEC J-STD-020. Suitable for use in SnPb or Pb-free soldering processes. Typical Application Circuit RT9179A VIN R1 Chip Enable C3 0.1uF VOUT VOUT VIN C1 1uF EN GND VOUT = 1.175 x ( 1 + ADJ R2 C2 3.3uF R1 ) Volts R2 Note: R2 around 200k is recommended. Refer to the "Application Information" for COUT selection. DS9179A-08 April 2011 www.richtek.com 1 RT9179A Functional Pin Description Pin No. Pin Name Pin Function 2 VIN Power Input Voltage 5, 6, 7, 8 GND Ground 1 EN Chip Enable (Active High) 4 ADJ 3 VOUT Adjust Output Voltage. The output voltage is set by the external feedback resistors connecting to ADJ pin and is calculated as : VOUT = 1.175 x (1 + R1 ) Volts R2 Output Voltage Function Block Diagram EN Current-Limit and Thermal Protection Shutdown and Logic Control VIN Thermal SHDN 1.175V VREF +_ Error Amplifier MOS Driver VOUT ADJ GND www.richtek.com 2 DS9179A-08 April 2011 RT9179A Absolute Maximum Ratings (Note 1) Supply Input Voltage ----------------------------------------------------------------------------------------------- 6V Power Dissipation, PD @ TA = 25C, TJ = 125C SOP-8 ------------------------------------------------------------------------------------------------------------------ 1.67W Package Thermal Resistance (Note 2) SOP-8, JA ------------------------------------------------------------------------------------------------------------ 60C/W Lead Temperature (Soldering, 10 sec.) ------------------------------------------------------------------------- 260C Junction Temperature ----------------------------------------------------------------------------------------------- 150C Storage Temperature Range -------------------------------------------------------------------------------------- -65C to 150C ESD Susceptibility (Note 3) HBM (Human Body Mode) ----------------------------------------------------------------------------------------- 2kV MM (Machine Mode) ------------------------------------------------------------------------------------------------ 200V Recommended Operating Conditions (Note 4) Supply Input Voltage ----------------------------------------------------------------------------------------------- 3V to 5.5V Enable Input Voltage ----------------------------------------------------------------------------------------------- 0V to 5.5V Junction Temperature Range -------------------------------------------------------------------------------------- -40C to 125C Electrical Characteristics (VIN = VOUT + 0.7V, IOUT = 10A, CIN = 1F, COUT = 3.3F (Ceramic), TA = 25C unless otherwise specified) Parameter Symbol Test Conditions Min Typ Max Unit Reference Voltage Tolerance VREF 1.163 1.175 1.187 V Adjust Pin Current IADJ -- -- 10 nA Output Voltage Range VOUT 1.175 -- 4.5 V Quiescent Current IQ Enabled, IOUT = 0mA -- 150 -- A ISTBY V IN = 5.5V, Shutdown -- -- 1 A 700 -- -- mA IOUT = 10mA -- 10 -- IOUT = 500mA -- 400 -- V OUT + 0.7V < VIN < 5.5V & 3.3V < VIN < 5.5V -- 0.001 -- %/V Standby Current (Note 5) (Note 6) Current Limit Dropout Voltage ILIM (Note 7) VDROP mV Line Regulation VLINE Thermal Shutdown Temperature TSD -- 170 -- C Thermal Shutdown Hysteresis TSD -- 40 -- C -- -- 0.4 2.0 -- -- -- -- 10 EN Threshold Logic-Low Voltage VIL V IN = 3.3V, Shutdown Logic-High Voltage VIH V IN = 3.3V, Enable IEN V IN = VCE = 5.5V EN Current DS9179A-08 April 2011 V nA www.richtek.com 3 RT9179A Note 1. Stresses listed as the above "Absolute Maximum Ratings" may cause permanent damage to the device. These are for stress ratings. Functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may remain possibility to affect device reliability. Note 2. JA is measured in the natural convection at TA = 25C on the demo board, which has connected footprints as wide heat sink. Please see the thermal considerations on application information. Note 3. Devices are ESD sensitive. Handling precaution recommended Note 4. The device is not guaranteed to function outside its operating conditions. Note 5. Quiescent, or ground current, is the difference between input and output currents. It is defined by IQ = IIN - IOUT under no load condition (IOUT = 0mA). The total current drawn from the supply is the sum of the load current plus the ground pin current. Note 6. Standby current is the input current drawn by a regulator when the output voltage is disabled by a shutdown signal (VEN 0.4V). It is measured with VIN = 5.5V. Note 7. The dropout voltage is defined as VIN -VOUT, which is measured when VOUT is VOUT(NORMAL) - 100mV. www.richtek.com 4 DS9179A-08 April 2011 RT9179A Typical Operating Characteristics ADJ Pin Voltage vs. Temperature Output Voltage vs. Temperature 3.29 VIN = 5V R1 = 360K R2 = 200K VIN = 5V 1.19 ADJ Pin Voltage (V) 3.28 Output Voltage (V) 1.2 3.27 3.26 3.25 1.18 1.17 1.16 1.15 1.14 3.24 -50 -25 0 25 50 75 100 125 -50 -25 0 Temperature ( C) 25 50 75 100 125 Temperature ( C) Quiescent Current vs. Input Voltage Quiescent Current vs. Temperature 150 160 Quiescent Current (uA)1 Quiescent Current (uA) VIN = 5V 150 140 130 140 130 120 120 -50 -25 0 25 50 75 100 3 125 3.5 Temperature ( C) PSRR(dB) 0 600 VIN = 3.3V, VEN = 3.3V CIN = 1uF (X7R) COUT = 3.3uF (X7R) 5 5.5 VOUT = 3.3V, R1 = 360K, R2 = 200K CIN = 1uF (X7R) COUT = 3.3uF (X7R) 500 No Load -20 4.5 Dropout Voltage vs. Io PSRR IL = 100mA -40 IL = 10mA -60 -80 Dropout Voltage (mV) 20 4 Input Voltage (V) TJ = 125C 400 TJ = 25C 300 200 TJ = -40C 100 0 10 0.01 100 0.1 DS9179A-08 April 2011 1K 10K 100K 1 10 100 (Hz) Frequency (kHz) 1M 1000 0 100 200 300 400 500 Io (mA) www.richtek.com 5 RT9179A Current Limit vs. Temperature 1 VIN = 5V 2 Source Current (A) 0.95 Current Limit (A) Output Short-Circuit Protection 4 0.9 0.85 0.8 0.75 1 0.8 0.6 0.4 VIN = 5V R1 = 360k R2 = 200k CIN = 1uF COUT = 3.3uF 0.2 0 0.7 -50 -25 0 25 50 75 100 125 Time (1ms/Div) Temperature ( C) Load Transient Response Load Current(mA) 5 4 Output Voltage Deviation(mV) 10 0 -10 R1 = 360K, R2 = 200K CIN = 1uF(X7R) COUT = 3.3uF(X7R) VIN = 4V to 5V IO : 150mA Output Voltage Deviation(mV) Input Voltage Deviation(V) Line Transient Response 500 0 50 0 -50 CIN = 1uF (X7R) COUT = 3.3uF (X7R) Time (500us/Div) Time (250us/Div) Enable Threshold Voltage vs. Temperature Enable Response Enable Voltage(V) 0.9 0.7 6 4 2 0 VOUT TURN ON Output Voltage Deviation(V) Enable Threshold Voltage (V)1 1 0.8 VIN = 3.3V, R1 = 56K R2 = 200K VOUT TURN OFF 0.6 VIN =5V R1 =360k R2 =200k CIN =1uF COUT =3.3uF 3 2 1 0 IO : 150mA 0.5 -50 -25 0 25 50 75 Temperature ( C) www.richtek.com 6 100 125 Time (100us/Div) DS9179A-08 April 2011 RT9179A Application Information Input Capacitor An input capacitance of 1F is required between the device input pin and ground directly (the amount of the capacitance may be increased without limit). There are no requirements for the ESR on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will be 1F over the entire operating temperature range. Output Capacitor The RT9179A is designed specifically to work with very small ceramic output capacitors. The recommended minimum capacitance is 3.3F ceramic or tantalum capacitor between LDO output and GND for stability. But for output voltage lower than 1.35V, to use a minimum of 3.3F tantalum or electrolyte capacitor. Higher capacitance values help to improve transient. The output capacitor's ESR is critical because it forms a zero to provide phase lead which is required for loop stability. No Load Stability The device will remain stable and in regulation with no external load. This is specially important in CMOS RAM keep-alive applications DS9179A-08 April 2011 Region of Stable COUT ESR vs. Load Current 10.000 10 Region of Stable COUT ESR () Like any low-dropout regulator, the RT9179A requires input and output decoupling capacitors. These capacitors must be correctly selected for good performance (see Capacitor Characteristics Section). Please note that linear regulators with a low dropout voltage have high internal loop gains which require care in guarding against oscillation caused by insufficient decoupling capacitance. Region of Instable 1 1.000 0.100 0.1 Region of Stable 0.010 Region of Instable 0.001 0 100 200 300 400 500 Load Current (mA) Input-Output (Dropout) Voltage A regulator's minimum input-to-output voltage differential (dropout voltage) determines the lowest usable supply voltage. In battery-powered systems, this determines the useful end-of-life battery voltage. Because the device uses a PMOS, its dropout voltage is a function of drain-to-source on-resistance, RDS(ON), multiplied by the load current : VDROPOUT = VIN - VOUT = RDS(ON) x IOUT Current Limit The RT9179A monitors and controls the PMOS' gate voltage, minimum limiting the output current to 700mA. The output can be shorted to ground for an indefinite period of time without damaging the part. Short-Circuit Protection The device is short circuit protected and in the event of a peak over-current condition, the short-circuit control loop will rapidly drive the output PMOS pass element off. Once the power pass element shuts down, the control loop will rapidly cycle the output on and off until the average power dissipation causes the thermal shutdown circuit to respond to servo the on/off cycling to a lower frequency. Please refer to the section on thermal information for power dissipation calculations. www.richtek.com 7 RT9179A Capacitor Characteristics Tantalum : It is important to note that capacitance tolerance and variation with temperature must be taken into consideration when selecting a capacitor so that the minimum required amount of capacitance is provided over the full operating temperature range. In general, a good tantalum capacitor will show very little capacitance variation with temperature, but a ceramic may not be as good (depending on dielectric type). Solid tantalum capacitors are recommended for use on the output because their typical ESR is very close to the ideal value required for loop compensation. They also work well as input capacitors if selected to meet the ESR requirements previously listed. Aluminum electrolytics also typically have large temperature variation of capacitance value. Equally important to consider is a capacitor's ESR change with temperature: this is not an issue with ceramics, as their ESR is extremely low. However, it is very important in Tantalum and aluminum electrolytic capacitors. Both show increasing ESR at colder temperatures, but the increase in aluminum electrolytic capacitors is so severe they may not be feasible for some applications. Ceramic : For values of capacitance in the 10F to 100F range, Tantalums also have good temperature stability: a good quality tantalum will typically show a capacitance value that varies less than 10 to 15% across the full temperature range of 125C to -40C. ESR will vary only about 2X going from the high to low temperature limits. The increasing ESR at lower temperatures can cause oscillations when marginal quality capacitors are used (if the ESR of the capacitor is near the upper limit of the stability range at room temperature). Aluminum : This capacitor type offers the most capacitance for the money. The disadvantages are that they are larger in physical size, not widely available in surface mount, and have poor AC performance (especially at higher ceramics are usually larger and more costly than tantalums but give superior AC performance for by-passing high frequency noise because of very low ESR (typically less than 10m). However, some dielectric types do not have good capacitance characteristics as a function of voltage and temperature. frequencies) due to higher ESR and ESL. Z5U and Y5V dielectric ceramics have capacitance that drops severely with applied voltage. A typical Z5U or Y5V capacitor can lose 60% of its rated capacitance with half of the rated voltage applied to it. The Z5U and Y5V also exhibit a severe temperature effect, losing more than 50% of nominal capacitance at high and low limits of the temperature range. It should also be noted that many aluminum electrolytics only specify impedance at a frequency of 120Hz, which indicates they have poor high frequency performance. Only aluminum electrolytics that have an impedance specified at a higher frequency (between 20kHz and 100kHz) should be used for the device. Derating must be applied to the manufacturer's ESR specification, since it is typically only valid at room temperature. X7R and X5R dielectric ceramic capacitors are strongly recommended if ceramics are used, as they typically maintain a capacitance range within 20% of nominal over full operating ratings of temperature and voltage. Of course, they are typically larger and more costly than Z5U/Y5U types for a given voltage and capacitance. www.richtek.com 8 Compared by size, the ESR of an aluminum electrolytic is higher than either Tantalum or ceramic, and it also varies greatly with temperature. A typical aluminum electrolytic can exhibit an ESR increase of as much as 50X when going from 25C down to -40C. Any applications using aluminum electrolytics should be thoroughly tested at the lowest ambient operating temperature where ESR is maximum. DS9179A-08 April 2011 RT9179A Thermal Considerations The best way to do this is to layout CIN and COUT near the The RT9179A can deliver a current of up to 500mA over the full operating junction temperature range. However, the maximum output current must be derated at higher ambient temperature to ensure the junction temperature does not exceed 125C. With all possible conditions, the junction temperature must be within the range specified under operating conditions. Power dissipation can be calculated based on the output current and the voltage drop across regulator. device with short traces to the VIN, VOUT, and ground pins. The regulator ground pin should be connected to the external circuit ground so that the regulator and its capacitors have a "single point ground". PD (MAX) = ( TJ (MAX) - TA ) / JA Where TJ (MAX) is the maximum junction temperature of the die (125C) and T A is the maximum ambient temperature. The junction to ambient thermal resistance (JA is layout dependent) for SOP-8 package is 60C/W at recommended minimum footprint. Visit our website in which "Recommended Footprints for Soldering Surface Mount Packages" for detail. More power can be dissipated if the maximum ambient temperature of the application is lower. Approaches for enhancing thermal performance is improving the power dissipation capability of the PCB design like cooper area increases. flows through the traces going into VIN and coming from VOUT, Kelvin connect the capacitor leads to these pins so there is no voltage drop in series with the input and output capacitors. Optimum performance can only be achieved when the device is mounted on a PC board according to the diagram below: GND + Thermal protection limits power dissipation in RT9179A. When the operation junction temperature exceeds 170C, starts the thermal shutdown function and turns the pass element off. The pass element turns on again after the junction temperature reduced about 40C. Using a single point ground technique for the regulator and it's capacitors fixed the problem. Since high current EN ADJ VIN VOUT + The final operating junction temperature for any set of conditions can be estimated by the following thermal equation : + PD = (VIN - VOUT) IOUT + VIN IGND It should be noted that stability problems have been seen in applications where "vias" to an internal ground plane were used at the ground points of the device and the input and output capacitors. This was caused by varying ground potentials at these nodes resulting from current flowing through the ground plane. PCB Layout Good board layout practices must be used or instability can be induced because of ground loops and voltage drops. The input and output capacitors MUST be directly connected to the input, output, and ground pins of the device using traces which have no other currents flowing through them. DS9179A-08 April 2011 GND SOP-8 Board Layout www.richtek.com 9 RT9179A The RT9179ACS regulator is packaged in SOP-8 package. This package is unable to efficiently dissipate the heat generated when the regulator is operating at high power levels. In order to control die-operating temperatures, the PCB layout should allow for maximum possible copper area at the GND pins of the RT9179ACS. The multiple GND pins on the SOP-8 package are internally connected, but lowest thermal resistance will result if these pins are tightly connected on the PCB. This will also aid heat dissipation at high power levels. If the large copper around the IC is unavailable, a buried layer may be used as a heat sink. Use vias to conduct the heat into the buried or backside of PCB layer. Use vias to conduct the heat into the buried or backside of PCB layer. RT9179ACS (SOP-8) The PCB heat sink copper area should be solder-painted without masked. This approaches a "best case" pad heat sink. To prevent this maximum junction temperature from being exceeded, the appropriate power plane heat sink MUST be used. Higher continuous currents or ambient temperature require additional heatsinking. www.richtek.com 10 DS9179A-08 April 2011 RT9179A Outline Dimension H A M J B F C I D Dimensions In Millimeters Dimensions In Inches Symbol Min Max Min Max A 4.801 5.004 0.189 0.197 B 3.810 3.988 0.150 0.157 C 1.346 1.753 0.053 0.069 D 0.330 0.508 0.013 0.020 F 1.194 1.346 0.047 0.053 H 0.170 0.254 0.007 0.010 I 0.050 0.254 0.002 0.010 J 5.791 6.200 0.228 0.244 M 0.400 1.270 0.016 0.050 8-Lead SOP Plastic Package Richtek Technology Corporation Richtek Technology Corporation Headquarter Taipei Office (Marketing) 5F, No. 20, Taiyuen Street, Chupei City 5F, No. 95, Minchiuan Road, Hsintien City Hsinchu, Taiwan, R.O.C. Taipei County, Taiwan, R.O.C. Tel: (8863)5526789 Fax: (8863)5526611 Tel: (8862)86672399 Fax: (8862)86672377 Email: marketing@richtek.com Information that is provided by Richtek Technology Corporation is believed to be accurate and reliable. Richtek reserves the right to make any change in circuit design, specification or other related things if necessary without notice at any time. No third party intellectual property infringement of the applications should be guaranteed by users when integrating Richtek products into any application. No legal responsibility for any said applications is assumed by Richtek. DS9179A-08 April 2011 www.richtek.com 11